Observation of New Resonance Structure in the Invariant Mass Spectrum of Two gamma-Quanta in dC-Interactions at Momentum 2.75 GeV/c per Nucleon

TL;DR

This paper reports the discovery of a new resonance at approximately 355 MeV in the gamma-gamma invariant mass spectrum from deuteron-carbon interactions at 2.75 GeV/c per nucleon, with preliminary estimates of its width and cross section.

Contribution

It presents the first observation of a new resonance structure in the gamma-gamma invariant mass spectrum in dC interactions at this energy.

Findings

Resonance at M = 355 MeV observed

Estimated width of the resonance is 41 MeV

Cross section of the resonance is approximately 0.6 mb

Abstract

A new resonance structure at M = 355 \pm 6 \pm 9 MeV is observed in the invariant mass spectrum of two gamma-quanta produced in the reaction d + C => gamma + gamma + x at momentum 2.75 GeV/c per nucleon. Preliminary estimates of its width and cross section are Gamma = 41 \pm 12 MeV and sigma_{gamma-gamma} = 0.6 mkb. The collected statistics is 2680 \pm 310 events of 1.5 10^6 triggered interactions of a total number 3 10^{12} dC-interactions.